全新java初学者实践教程6(Java SE5.0版)
BP'36?=Zo 基本语法3
eL10Q(;P` 3G,Oba[$< [YF>:ydk 我们这个教程侧重的是实践的内容和语言的重点。在[font="Times]java语言中还有很多细节的东西,请参考[font="Times]sun公司的官方培训教程。我们这里不能一一讲述。这节课我们来给大家提供一些程序流程控制的一些例子供大家学习。计算机怎么做事情,是我们教给他的。我们用它解决实际生活中的问题,所以计算机要描述现实生活中的流程。[font="Times]Java语言中提供了[font="Times]4类程序控制语句,来描述流程:
nBjqTud
[R(`W#W [font="Times] 1.循环语句[font="Times]:while,do-while,for
Y!~49<; $+8cc\fq [font="Times]2.分支语句[font="Times]:if-else,switch,
Pk{_(ybaY [font="Times]
bv]`!g:
C 3.跳转语句[font="Times] break,continue,label: 和[font="Times]return
LSa,1{ [font="Times]
p4.wh|n 4.异常处理语句[font="Times]:try-catch-finally,throw
Se:.4< 2,$8icM 实践:
$2oTkOA [font="Times] 1.循环语句
"bFTk/ [font="Times] while 语句
&gVN& [font="Times]class While {
r?+%?$ [font="Times]public static void main(String args[]) {
H*RC@O_hv [font="Times]int n = 10;
0%9 q8M; [font="Times]while(n > 0) {
zT=Ho
[font="Times]System.out.println("tick " + n);
:~b3^xhc^ [font="Times]n--;
lGPUIoUo [font="Times]}
Bn=by{i [font="Times]}
f2Klt6"9 [font="Times]}
mXRB7k [font="Times] do…while 语句
B:b5UD [font="Times] class DoWhile {
ZXqSH${Tp [font="Times]public static void main(String args[]) {
B8.Pn [font="Times]int n = 10;
]
bM)t< [font="Times]do {
6}gls}[0{e [font="Times]System.out.println("tick " + n);
KyVQh8 [font="Times]n--;
ocqU=^ta [font="Times]} while(n > 0);
g`{;(/M+ [font="Times]}
wKtl+}} [font="Times]}
kw>v:F<M 二者区别,[font="Times]do…while至少循环一次,而[font="Times]while的表达式要是为[font="Times]flase的话可以一次也不循环。再通俗一点,[font="Times]do…while就算是括号里的是[font="Times]flase,人家最少也能[font="Times]do一次。
W]"zctE [font="Times] for语句
Tzt8h\Q^z [font="Times] class ForTick {
-[*,^Ti` [font="Times]public static void main(String args[]) {
SN9kFFIPb= [font="Times]int n;
&oP+$;Y [font="Times]for(n=10; n>0; n--)
3EV;LH L [font="Times]System.out.println("tick " + n);
k$R~R-' [font="Times]}
~Sg5:T3 [font="Times]}
b*;Si7- 与上面那两个的区别,[font="Times]for循环执行的次数是可以在执行之前确定的。通俗一点说吧,看这个例子[font="Times] for(n=10; n>0; n--)就是在括号里的时候,就已经知道要循环[font="Times]10次了。
9oyE$S h] 还有啊,[font="Times]for循环的部分可以为空的
04LI]' [font="Times]class ForVar {
NO7J!k? [font="Times]public static void main(String args[]) {
+6sy-<ZL: [font="Times]int i;
Ed0QQyC@9 [font="Times]boolean done = false;
_(_a*ml [font="Times]i = 0;
**w!CaqvY [font="Times]for( ; !done; ) {
(yu/l6[ [font="Times]System.out.println("i is " + i);
' KWyx [font="Times]if(i == 10) done = true;
;+W#5<i [font="Times]i++;
u!!Y=!y*< [font="Times]}
oz,np@f)J [font="Times]}
Jv>gwV{ [font="Times]}
循环语句的例子下载 j#X.KM [font="Times] 2.分支语句[font="Times]
s[M?as [font="Times] if/else语句
a=1NED' [font="Times]class IfElse {
N+m)/x
=: [font="Times]public static void main(String args[]) {
nGpXI\K [font="Times]int month = 4; // April
T}Km?d [font="Times]String season;
xHUsFms [font="Times]if(month == 12 || month == 1 || month == 2)
`n#H5Oyn [font="Times]season = "Winter";
Pj#<K%Bz [font="Times]else if(month == 3 || month == 4 || month == 5)
Gy9$wH@8 [font="Times]season = "Spring";
]mo-rhDsM [font="Times]else if(month == 6 || month == 7 || month == 8)
X\`_3= [font="Times]season = "Summer";
|8&,b`Gfo [font="Times]else if(month == 9 || month == 10 || month == 11)
:Ux?, [font="Times]season = "Autumn";
X>1,!I9 [font="Times]else
sT !~J4 [font="Times]season = "Bogus Month";
3VsW@SG7N [font="Times]System.out.println("April is in the " + season + ".");
%zA;+s$l [font="Times]}
q
0$,*[PH [font="Times]}
2QD3&Q9 [font="Times]//这段程序输出[font="Times]:
3*]eigi) [font="Times]//April is in the Spring.
*S]Ci\{_ [font="Times]// 注意[font="Times] “[font="Times]||”是或运算
Q}1 R5@7 [font="Times] switch语句
[=E [font="Times] class Switch {
&R[ Mc-2 [font="Times]public static void main(String args[]) {
*EOdEFsR/ [font="Times]int month = 4;
?^H
`M|S [font="Times]String season;
_g+JA3sIJ [font="Times]switch (month) {
Vu)4dD! [font="Times]case 12:
"oTHq]Ku [font="Times]case 1:
WB?jRYp [font="Times]case 2:
OP~HdocB [font="Times]season = "Winter";
)T/0S$@ [font="Times]break;
DNOueU [font="Times]case 3:
x^HGVWw_ [font="Times]case 4:
SFB~
->db [font="Times]case 5:
hU(umL< [font="Times]season = "Spring";
W}3.E "K [font="Times]break;
"8c@sHk(w [font="Times]case 6:
"w^!/ [font="Times]case 7:
xe#FUS
3 [font="Times]case 8:
yyoqX"v[ [font="Times]season = "Summer";
nc~F_i= [font="Times]break;
s:OFVlC%\ [font="Times]case 9:
1/RsptN"v [font="Times]case 10:
aK&b{d [font="Times]case 11:
j K!Au [font="Times]season = "Autumn";
FemCLvu [font="Times]break;
NiWa7 /Hr [font="Times]default:
;'?l$
._ [font="Times]season = "Bogus Month";
G,$PV
e* [font="Times]}
z{[xze-f [font="Times]System.out.println("April is in the " + season + ".");
Qt iDTr [font="Times]}
<A[E:*`* [font="Times]}
分支语句代码下载 ~"!]
3C,L AuUde$l_ [font="Times]switch语句适合于条件非常多的逻辑
Y,GU%[+ 请看上述语句可以混合使用,请看
下载例子